Mechanistic Insights into Stereoselective Catalysis—The Effects of Counterions in a CuII–Bissulfoximine-Catalyzed Diels–Alder Reaction

C2-Symmetric Bissulfoximine Based Metal Complexes: Synthesis, Characterization and their Electrocatalytic activity in Oxygen Reduction Reaction

Sulfoximine-based metal complexes have gained much interest in recent years owing to their promising properties in synthetic organic chemistry. These sulfoximines have been recently introduced in the field of organometallics. However, the coordination properties of pincer sulfoximine ligands and their metal complexes have never been reported. Here in this work a C 2 -symmetric bissulfoximine based pincer ligand ((pyridine-2,6-diylbis(methylene))bis(azaneylylidene))bis(diphenyl-λ 6 -sulfanone) namely S-P ligand and its metal [M(SP) 2 ] 2+ {M = Fe ( SC-1 ), Co ( SC-2 ), Ni ( SC-3 ), Cu ( SC-4 )} complexes were synthesized. The complexes were characterized by different spectroscopic techniques like UV-Vis, IR, NMR, ESI-MS, and single-crystal XRD. Complexes SC-1 and SC-3 exhibited octahedral geometry irrespective of the metal center. The complexes were systematically explored for electrocatalytic oxygen reduction reaction (ORR) by immobilizing them on a glassy carbon electrode using Nafion. These complexes showed selective 2e - catalytic reduction of O 2 to H 2 O 2 in which complex SC-4 showed the highest activity with an onset potential of 0.75 V and complex SC-2 showed the highest selectivity (≈ 90%). This could be viewed as a promising candidate as an electrocatalyst for electrochemical hydrogen peroxide synthesis.

Using chiral ionic liquid additives to enhance asymmetric induction in a Diels–Alder reaction

A bis-oxazoline ligand has been complexed using Cu(ii) and Zn(ii) trifluoromethanesulfonate and a range of chiral ionic liquid (CIL) additives based on natural products were used as a co-catalyst for a Diels–Alder reaction.